At present, a wide variety of industrial processes for producing or processing objects have been developed and carried out, and the types of gases discharged from such a wide variety of industrial processes (hereinafter, referred to as “processing target exhaust gas”) are also very diverse. Thus, various types of gas processing methods and exhaust gas processing devices are selectively used according to the types of processing target exhaust gas discharged from industrial processes.
For example, in a semiconductor production process, various kinds of gases are used, such as monosilane (SiH4), chloride gas, PFC (perfluorinated compounds: CF4, SF6, C4F8, NF3, C5F8, C4F6, C2F6, C3F8, C3F6, CH2F2, CHF3, etc., those compounds have a great impact on the global environment, since the global warming potential (GWP) values thereof are higher by several thousand times to several ten thousand times than that of CO2 and thus very high, and the atmospheric lifetimes thereof are also longer by several thousand times to several ten thousand times than that of CO2 and thus very long). In the case where monosilane is included in the processing target exhaust gas, a processing device such as a pyrolysis type, a combustion type, an adsorption type, or a chemical reaction type is used. In the case where chloride gas is included in the processing target exhaust gas, a processing device such as a wet type using a chemical solution, or an adsorption type is used. In addition, in the case where PFC is included in the processing target exhaust gas, an exhaust gas processing device such as a catalyst type, a thermal reaction type, a pyrolysis type, a combustion type, or a plasma type is used.
When exhaust gas processing devices are respectively prepared according to various types of processing target exhaust gas discharged from industrial processes as described above, management of such devices becomes complicated for a user, and the time and cost required for maintenance of the devices increase. This consequently have a rebound effect on the cost of the product, leading to a decrease in cost competitiveness of the product.
Many types of the processing target exhaust gas discharged from industrial processes can be thermally decomposed under high temperature. Thus, when a pyrolysis type exhaust gas processing device disclosed in Patent Literature 1 is used, that is, a device is used which performs decomposition processing by emitting an atmospheric pressure plasma into a reactor and supplying processing target exhaust gas toward the atmospheric pressure plasma, at least a processing target exhaust gas that can be thermally decomposed under high temperature can be decomposed with one device regardless of the type of the processing target exhaust gas. In the present specification, “atmospheric pressure plasma” is a plasma generated under an atmospheric pressure condition, and means plasma in a broad sense including thermal plasma, microwave plasma, and flame.